Paul Govaert

Automated neonatal seizure detection mimicking a human observer reading EEG

OBJECTIVE The description and evaluation of a novel patient-independent seizure detection for the EEG of the newborn term infant. METHODS We identified characteristics of neonatal seizures by which a human observer is able to detect them. Neonatal seizures were divided into two types. For each type, a fully automated detection algorithm was developed based on the identified human observer characteristics. The first algorithm analyzes the correlation between high-energetic segments of the EEG. The second detects increases in low-frequency activity (<8 Hz) with high autocorrelation. RESULTS The complete algorithm was tested on multi-channel EEG recordings of 21 patients with and 5 patients without electrographic seizures, totaling 217 h of EEG. Sensitivity of the combined algorithms was found to be 88%, Positive Predictive Value (PPV) 75% and the false positive rate 0.66 per hour. CONCLUSIONS Our approach to separate neonatal seizures into two types yields a high sensitivity combined with a good PPV and much lower false positive rate than previously published algorithms. SIGNIFICANCE The proposed algorithm significantly improves neonatal seizure detection and monitoring.

Perinatal cortical infarction within middle cerebral artery trunks

AIM To define neonatal pial middle cerebral artery infarction. METHODS A retrospective study was made of neonates in whom focal arterial infarction had been detected ultrasonographically. A detailed study was made of cortical middle cerebral artery infarction subtypes. RESULTS Forty infarctions, with the exception of those in a posterior cerebral artery, were detected ultrasonographically over a period of 10 years. Most were confirmed by computed tomography or magnetic resonance imaging. Factor V Leiden heterozygosity was documented in three. The onset was probably antepartum in three, and associated with fetal distress before labour in one. There were 19 cases of cortical middle cerebral artery stroke. The truncal type (n=13) was more common than complete (n = 5) middle cerebral artery infarction. Of six infarcts in the anterior trunk, four were in term infants and five affected the right hemisphere. Clinical seizures were part of the anterior truncal presentation in three. One of these infants, with involvement of the primary motor area, developed a severe motor hemisyndrome. The Bayley Mental Developmental Index was above 80 in all of three infants tested with anterior truncal infarction. Of seven patients with posterior truncal infarction, six were at or near term. Six of these lesions were left sided. Clinical seizures were observed in three. A mild motor hemisyndrome developed in at least three of these infants due to involvement of parieto-temporal non-primary cortex. CONCLUSIONS Inability to differentiate between truncal and complete middle cerebral artery stroke is one of the explanations for the reported different outcomes. Severe motor hemisyndrome can be predicted from neonatal ultrasonography on the basis of primary motor cortex involvement. Clinical seizures were recognised in less than half of the patients with truncal infarction; left sided presentation was present in the posterior, but not the anterior truncal type of infarction. Asphyxia is a rare cause of focal arterial infarction.

Neonatal Cerebral Sinovenous Thrombosis From Symptom to Outcome

Background and Purpose— Cerebral sinovenous thrombosis is a rare disease with severe neurological sequelae. The aim of this retrospective multicenter study was to investigate the clinical course, possible risk factors, and outcome of a cohort of neonatal patients with sinovenous thrombosis and, second, to estimate the incidence in The Netherlands. Methods— From January 1999 to March 2009, a review of all neonatal patients with sinovenous thrombosis from 6 tertiary neonatal intensive care units was performed. Population characteristics, clinical presentation, (prothrombotic) risk factors, neuroimaging, interventions, and neurodevelopment were evaluated. An estimated incidence was calculated based on the Netherlands Perinatal Registry. Results— Fifty-two neonates were included (39 boys) with a median gestational age of 39 weeks (range, 30 to 42 weeks; 5 preterm). An assisted or complicated delivery occurred in 32 of 52. Presenting symptoms developed at a median postnatal age of 1.5 days (range, 0 to 28 days) and consisted mainly of seizures (29 of 52). All sinovenous thrombosis cases were confirmed with MRI/MR venography. Multisinus thrombosis was most common followed by superior sagittal sinus thrombosis. FII G20210A mutation was present in 2 of 18 tested neonates (11%). Anticoagulation therapy (in 22 of 52) did not result in hemorrhagic complications. At follow-up (median age, 19 months; range, 3 to 72 months), moderate to severe neurological sequelae were present in 38%. The mortality was 10 of 52 (19%). A variable, although high yearly incidence of 1.4 to 12 per 100 000 term newborns was found. Conclusions— Neonatal sinovenous thrombosis is a multifactorial disease. The estimated incidence in The Netherlands seems higher than reported elsewhere.

Mutation in the AP4M1 Gene Provides a Model for Neuroaxonal Injury in Cerebral Palsy

Cerebral palsy due to perinatal injury to cerebral white matter is usually not caused by genetic mutations, but by ischemia and/or inflammation. Here, we describe an autosomal-recessive type of tetraplegic cerebral palsy with mental retardation, reduction of cerebral white matter, and atrophy of the cerebellum in an inbred sibship. The phenotype was recorded and evolution followed for over 20 years. Brain lesions were studied by diffusion tensor MR tractography. Homozygosity mapping with SNPs was performed for identification of the chromosomal locus for the disease. In the 14 Mb candidate region on chromosome 7q22, RNA expression profiling was used for selecting among the 203 genes in the area. In postmortem brain tissue available from one patient, histology and immunohistochemistry were performed. Disease course and imaging were mostly reminiscent of hypoxic-ischemic tetraplegic cerebral palsy, with neuroaxonal degeneration and white matter loss. In all five patients, a donor splice site pathogenic mutation in intron 14 of the AP4M1 gene (c.1137+1G-->T), was identified. AP4M1, encoding for the mu subunit of the adaptor protein complex-4, is involved in intracellular trafficking of glutamate receptors. Aberrant GluRdelta2 glutamate receptor localization and dendritic spine morphology were observed in the postmortem brain specimen. This disease entity, which we refer to as congenital spastic tetraplegia (CST), is therefore a genetic model for congenital cerebral palsy with evidence for neuroaxonal damage and glutamate receptor abnormality, mimicking perinatally acquired hypoxic-ischemic white matter injury.

White matter damage in neonatal enterovirus meningoencephalitis

The authors report six neonates with enteroviral meningoencephalitis. Five infants presented with prolonged seizures, and one presented with systemic enteroviral disease. Cranial ultrasonography showed increased echogenicity in the periventricular white matter, and MRI confirmed mild to severe white matter damage in all infants, which looked similar to periventricular leukomalacia. Two infants developed cerebral palsy: one was neurologically suspect at age 18 months, and three were developmentally normal.

Oligohydramnios, renal insufficiency, and ileal perforation in preterm infants after intrauterine exposure to indomethacin

Three preterm infants exposed antenatally to indomethacin developed a characteristic syndrome consisting of edema and hydrops with a bleeding disorder at birth, oliguric renal failure during the first 3 postnatal days, and acute pneumoperitoneum resulting from localized ileal perforation(s) at the end of the first week of life. Despite the value of indomethacin for arresting preterm labor, the physician must take into account the potential hazards of drug toxicity.

Mutation of the iron-sulfur cluster assembly gene IBA57 causes severe myopathy and encephalopathy

Two siblings from consanguineous parents died perinatally with a condition characterized by generalized hypotonia, respiratory insufficiency, arthrogryposis, microcephaly, congenital brain malformations and hyperglycinemia. Catalytic activities of the mitochondrial respiratory complexes I and II were deficient in skeletal muscle, a finding suggestive of an inborn error in mitochondrial biogenesis. Homozygosity mapping identified IBA57 located in the largest homozygous region on chromosome 1 as a culprit candidate gene. IBA57 is known to be involved in the biosynthesis of mitochondrial [4Fe-4S] proteins. Sequence analysis of IBA57 revealed the homozygous mutation c.941A > C, p.Gln314Pro. Severely decreased amounts of IBA57 protein were observed in skeletal muscle and cultured skin fibroblasts from the affected subjects. HeLa cells depleted of IBA57 showed biochemical defects resembling the ones found in patient-derived cells, including a decrease in various mitochondrial [4Fe-4S] proteins and in proteins covalently linked to lipoic acid (LA), a cofactor produced by the [4Fe-4S] protein LA synthase. The defects could be complemented by wild-type IBA57 and partially by mutant IBA57. As a result of the mutation, IBA57 protein was excessively degraded, an effect ameliorated by protease inhibitors. Hence, we propose that the mutation leads to partial functional impairment of IBA57, yet the major pathogenic impact is due to its proteolytic degradation below physiologically critical levels. In conclusion, the ensuing lethal complex biochemical phenotype of a novel metabolic syndrome results from multiple Fe/S protein defects caused by a deficiency in the Fe/S cluster assembly protein IBA57.

Automated artifact removal as preprocessing refines neonatal seizure detection

OBJECTIVE The description and evaluation of algorithms using Independent Component Analysis (ICA) for automatic removal of ECG, pulsation and respiration artifacts in neonatal EEG before automated seizure detection. METHODS The developed algorithms decompose the EEG using ICA into its underlying sources. The artifact source was identified using the simultaneously recorded polygraphy signals after preprocessing. The EEG was reconstructed without the corrupting source, leading to a clean EEG. The impact of the artifact removal was measured by comparing the performance of a previously developed seizure detector before and after the artifact removal in 13 selected patients (9 having artifact-contaminated and 4 having artifact-free EEGs). RESULTS A significant decrease in false alarms (p=0.01) was found while the Good Detection Rate (GDR) for seizures was not altered (p=0.50). CONCLUSIONS The techniques reduced the number of false positive detections without lowering sensitivity and are beneficial in long term EEG seizure monitoring in the presence of disturbing biological artifacts. SIGNIFICANCE The proposed algorithms improve neonatal seizure monitoring.

Diagnosis of perinatal stroke I: Definitions, differential diagnosis and registration

Introduction:  Perinatal stroke can be divided into three subtypes: ischaemic stroke, either arterial or sinovenous and haemorrhagic stroke. For the sake of universal registration and to perform intervention studies, we propose a detailed diagnostic registration system for perinatal stroke taking 10 variables into account. These variables are discussed here and in the accompanying article.

COL4A2 mutation associated with familial porencephaly and small-vessel disease

Familial porencephaly, leukoencephalopathy and small-vessel disease belong to the spectrum of disorders ascribed to dominant mutations in the gene encoding for type IV collagen alpha-1 (COL4A1). Mice harbouring mutations in either Col4a1 or Col4a2 suffer from porencephaly, hydrocephalus, cerebral and ocular bleeding and developmental defects. We observed porencephaly and white matter lesions in members from two families that lack COL4A1 mutations. We hypothesized that COL4A2 mutations confer genetic predisposition to porencephaly, therefore we sequenced COL4A2 in the family members and characterized clinical, neuroradiological and biochemical phenotypes. Genomic sequencing of COL4A2 identified the heterozygous missense G1389R in exon 44 in one family and the c.3206delC change in exon 34 leading to frame shift and premature stop, in the second family. Fragmentation and duplication of epidermal basement membranes were observed by electron microscopy in a c.3206delC patient skin biopsy, consistent with abnormal collagen IV network. Collagen chain accumulation and endoplasmic reticulum (ER) stress have been proposed as cellular mechanism in COL4A1 mutations. In COL4A2 3206delC fibroblasts we detected increased rates of apoptosis and no signs of ER stress. Mutation phenotypes varied, including porencephaly, white matter lesions, cerebellar and optic nerve hypoplasia and unruptured carotid aneurysm. In the second family however, we found evidence for additional factors contributing to the phenotype. We conclude that dominant COL4A2 mutations are a novel major risk factor for familial cerebrovascular disease, including porencephaly and small-vessel disease with reduced penetrance and variable phenotype, which might also be modified by other contributing factors.